[26.03] Stars Below the Horizontal Branch in M 92. II.

A. G. D. Philip (ISO and Union College)

The identification of a group of stars found below the
horizontal branch in the globular cluster M 92 has been
described in earlier papers. A review paper (Philip, 1996,
Baltic Astronomy 5, 425) presents some four-color plots
showing the location of various types of stars on, and near
the horizontal branch. A natural group of less luminous
stars has been found in plots of the four-color data.
Additional studies have ruled out random errors in the
photometry causing this grouping of stars about half a
magnitude below the horizontal branch. If a BHB star forms
an optical pair with one of the fainter, redder stars on the
main-sequence, the combination would result in a star with a
somewhat higher luminosity and a redder color. The new
position of the star in the HR diagram does not go through
the positions occupied by the new group below the HB. Also,
the distribution of such points does not scatter near the
HB and thin out as one gets further away from the HB.
Instead the HR diagram shows a region empty of points and
then a distinct group of stars. Recently I have found some
new CM-Diagrams of M 92, by other investigators, which show
the same distribution of stars. Investigations are now
underway at the VATT, on Mt. Graham, Arizona, to investigate
these stars in the Strömvil system (Strai\vzys,
Crawford and Philip, 1996, Baltic Astronomy 5, 84).

The author(s) of this abstract have provided an email address for comments about the abstract: AGDP@GAR.UNION.EDU